Effects Of Water Stress On Physiological And Biochemical Characteristics Of Three Ground Cover Plants

The physiological mechanism of drought-resistance in three landscape ground cover plants was studied, with species Belamcanda chinensis, Iris tectorum, Iris germanica and under manual controlling soil water environments, some mainly physiological and biological indices including chlorophyll changes, enzyme activities and osmotic adjustment et al were measured in different drought stress of three species. A drought simulating test was conducted and the specific method was adapted from Hsiao (1973), in which four levels of gradient of water contents were set up such as: the check (CK) 75-80% (percentage of maximum water hold capacity of the soil); the slight stress (T1) 55%-60%; moderate stress (T2) 40-45% and the severe stress (T3) 30-35%. The total of four sets of data were taken with an interval of 10 days. The main results showed as followings:1. As long as the increasing of stress intensity and lengthening of stress durations, the contents of total chlorophyll and chl a/b appeared an obvious declining trend with different degrees for three species. Among those decline amounts Belamcanda chinensis is the least, and Iris tectorum is the most. The total chlorophyll of Iris germanica appeared an obvious increasing trends during the middle time of the slight stress, which indicated that the total chlorophyll appeared relative concentration phenomenon.2. The contents of praline, soluble sugar and soluble protein, which are related to osmotic adjustment ability, appeared different changes trend in different species. The contents of praline and soluble sugar of Belamcanda chinensis and Iris germanica appeared increasing trends, while appeared obvious declining trends in Iris tectorum during the end of the moderate stress and the severe stress. The soluble protein content of three species appeared increasing trends under the slight stress, and as the enhancing of stress intensity and the enhancing of stress duration the contents of soluble protein showed a significant declining trends.3. Under drought stress condition, the activities of SOD, POD and CAT of Belamcanda chinensis and Iris germanica appeared an obvious enhancing trend. Iris tectorum appeared the same enhancing trend as those two species at the early stage of stress treatment, while appeared a declining trend as enlonging of treatment duration. 4. As long as the increasing of stress intensity and lengthening of stress durations, the contents of MDA appeared an obvious declining trend with different degrees for three species. The changing interval of Belamcanda chinensi is least, and of Iris tectorum is most.5. As long as the increasing of stress intensity and lengthening of stress durations, the electric leakage appeared an obvious declining trend with different degrees for three species. The changing interval of Iris germanica is least, and of Iris tectorum is most. Thus it can be seen that three species have better drought resistance, and they can resistant to slight water stress, so they can be suitable as a water-saving landscape plants to promote. Belamcanda chinensis and Iris germanica can tolerate short-term moderate and severe water stress, may be applicated in relatively water-poor cities.